Fig. 1

The Lys-biosensor based programming ALE process. The Lys biosensor senses the intracellular Lys concentration and regulates the expression level of the evolution actuator, thereby controls and indicates the evolution process. a Schematic of programming ALE process. The evolutionary strain SZ06/pMK was repeatedly and continuously cultured for several rounds in the same medium, the evolution process was ceased and the evolved cells were harvested when the relative eGFP fluorescence intensity no longer reduced significantly. Then, 22 single colonies were picked randomly for purification, and they were cultured in 24 deep-well plate. b The work diagram of pMK. When Lys concentration is higher, the biosensor was activated, thereby activating the expression of cdd and egfp and increasing the mutation rate and the eGFP fluorescence intensity of cells. When Lys concentration is lower, the Lys biosensor will not be activated, the relative eGFP fluorescence intensity will be decreased and the evolution process was ceased. c The change of relative eGFP fluorescence intensity in the 3^rd round. d The relative eGFP fluorescence intensity (solid line) and biomass (dotted line) of SZ06/pMK at 48 h of each round